1. Field of the Invention
The present invention relates to an optical information recording medium, and more particularly to a direct-read-after write (DRAW) type of an optical information recording medium comprising a substrate and a recording layer comprising a composition of at least gold and sulfur, with the content of the gold being 50 atomic percent or more in the composition.
2. Discussion of Background
In recent years, information recording media utilizing high density energy beams such as laser beams have been developed. These have been widely applied, in particular to compact disks (CD) used for audio reproduction such as music and the like. These conventional audio CDs are provided with pits which are preformed in the substrate, and exclusively used for audio reproduction. Because data recording and editing are not possible with this type of CD, the development of a direct-read-after-write (DRAW) type of CD is desired. More specifically, there is a demand for a DRAW-type CD having a high reflectance of 70% or more, which is capable of performing recording and reproduction operations at a low linear speed of 1.2 to 1.4 m/s.
Conventional optical information recording media have been developed mainly as memories for use with computers. For recording materials used in the recording layer of the conventional optical information recording media, metals with a low melting point such as tellurium and the like, and organic dyes are used in practice.
However, when these materials are used in the recording layers of DRAW-type CDs, the metals with a low melting point such as tellurium have the drawback that recording and reproduction at a low linear speed is very difficult because such low-melting-point metals provide recording layers with a high heat conductivity. In addition, a material with high reflectance which can record at a high sensitivity has not yet been developed. Also, because organic dyes have low heat conductivities they are suitable for recording and reproduction at low linear velocities, but a material with a reflectance of 70% or more containing an organic dye has not yet been discovered.